1. Field of the Invention
The present invention relates generally to virtual environment devices and more specifically it relates to a memory wire Braille tactile system for continuously replicating a plurality of Braille characters on a single display which is substantially less costly than conventional prior art and allows the user to maintain their level of touch sensitivity.
Shape memory alloys have been know and available for many years and have been proposed as operative in various types of devices. Preferably, the shape memory alloy utilized is a nickel-titanium alloy called Nitinol or Tinel, although copper based alloys have been used in many similar applications. Wires constructed from the memory alloy have a deformed shape when at cooler temperature called its martensitic state and return to their preset shape when heated above a transition temperature range called the austenitic state which the alloy is much stronger and stiffer than when in the martensitic state. When the memory wire is heated above the transition temperature range, the alloy remembers its original preset shape and tends to return to that shape.
2. Description of the Prior Art
There are numerous virtual environment devices. For example, U.S. Pat. No. 5,583,478 to Renzi; U.S. Pat. No. 4,945,727 to Whitehead et al; U.S. Pat. No. 5,496,174 to Garner; U.S. Pat. No. 5,226,619 to Alger; U.S. Pat. No. 5,129,753 to Wesley et al; U.S. Pat. No. 5,419,133 to Schneider; U.S. Pat. No. 4,932,210 to Julien et al; U.S. Pat. No. 4,761,955 to Bloch; U.S. Pat. No. 5,293,464 to Hirano et al; U.S. Pat. No. 5,127,228 to Swenson; U.S. Pat. No. 5,410,290 to Cho; U.S. Pat. No. 5,396,769 to Brudnicki; U.S. Pat. No. 4,700,541 to Gabriel et al; U.S. Pat. No. 5,275,219 to Giacomelall are illustrative of such prior art.
Renzi (U.S. Pat. No. 5,583,478) discloses a virtual environment tactile system comprised of a plurality of individual actuators controlled by a computer and associated drive electronics. Each actuator is comprised of a rare earth magnet and an associated contactor which selectively engages the user's skin resulting in the sensation of touch. Renzi does not utilize memory wires to actuate the contactor and does not allow the user to reposition his or her hand in relation to the contactors to maintain their sensitivity.
Whitehead et al (U.S. Pat. No. 4,945,727) discloses a hydraulic shape member alloy actuator comprising a uniaxial shape memory wire and a pair of hydraulic cylinders in fluid communication with each other. The first hydraulic cylinder is moved from a first position to a second position when the memory wire changes states upon heating.
Wesley et al (U.S. Pat. No. 5,129,753) discloses a shape memory wire latch mechanism for releasably connecting two separable structural members. The shape memory wire disengages the latch elements when heated above its transition temperature which allows the structural members to separate.
While these devices may be suitable for the particular purpose to which they address, they are not as suitable for continuously replicating a plurality of Braille characters on a single display which is substantially less costly than conventional prior art and allows the user to maintain their level of touch sensitivity by allowing the user to reposition their fingers. The prior art teaches complex devices which are costly to construct. Also, because of the complexity of the prior art, they are prone to malfunctioning.
In these respects, the memory wire Braille tactile system according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of continuously replicating a plurality of Braille characters on a single display which is substantially less costly than conventional prior art and allows the user to maintain their level of touch sensitivity.